Mechanical behavior of reinforced flexible pipe subjected to tensile force

Flexible pipelines must be designed considering the extreme situation for which additional components are needed against severe loading and environmental conditions. Tensile armor is employed in case of high tensile force, which increases with weight, so for deep water depth and heavy components used against high internal and external pressures. In this work, the mechanical behavior of the pipe under pure tension is investigated by both theoretical and numerical analysis. The latter model tries to be as real as possible to quantify the reliability of the assumption in the theoretical model and the relationship between axial loads, moreover, extension was carried out. The deformation along the longitudinal direction is function of the radial contact pressure among layers, thus for the theoretical model, an equivalent configuration for the pressure armor based on radial stiffness considerations has been developed and the longitudinal reaction force of the elements with winding angle close to 90° was not taken into account to be on the safe side. The plastic behavior of the PE layers was considered. This work aims to evaluate the need of tensile armor with respect to the steel strip reinforced thermoplastic pipeline (SSRTP) case for different diameters and water depths. The results obtained from the theoretical and the numerical simulations leads to a remarkable confidence in the models thanks to a relatively small shift achieved between the outcomes.